I came across this in Strabo
Excerpt from Book VII. Chapter III. 8. Getae.
…But what occasion is there for me to speak of such as belonged to the times of old? for Alexander (the Great), the son of Philip, in his campaign against the Thracians beyond Mount Haemus,(1) is said to have penetrated as far as this in an incursion into the country of the Triballi, and observed that they occupied the territory as far as the Danube and the island Peuce,(2) which is in it, and that the Getae possessed the country beyond that river; however, he was unable to pass into the island for want of
(2) Piczina, at the embouchure of the Danube, between Babadag and Ismail.
Dictionary of Greek and Roman Geography (1854)
William Smith, LLD, Ed.
PEUCE (Πεύκη, Ptol. 3.10.2; Strab. vii. p.305), an island of Moesia Inferior, formed by the two southernmost mouths of the Danube. It derived its name from the abundance of pine-trees which grew upon it. (Eratosth. in Schol. Apollon. 4.310.) It was of a triangular shape (Apollon. l.c.), and as large as Rhodes. By Martial (7.84. 3) it is called a Getic island; by Valerius Flaccus (8.217) a Sarmatian one. It has been identified with the modern island of Piczina or St. George, between Badabag and Ismail; but we must recollect that these parts were but little known to the ancients, and that in the lapse of time the mouths of the Danube have undergone great alterations. (Plin. Nat. 4.12. s. 24; Mela, 2.7; Avien. Descr. Orb. 440; Dion. Perieg. 401; Claud. IV Cons. Honor. 630, &c.)
PLINY Natural History Book IV
and from the point where it first enters Illyria it is called the Hister; after receiving 60 tributary rivers, nearly half of which are navigable, it is discharged into the Black Sea by six vast channels. The first of these is the mouth of Piczina, close to the island of that name, at which the nearest channel, called the Holy River, is swallowed up in a marsh 19 miles in extent. Opening from the same channel and above Istere spreads a lake measuring 63 miles round, named the Saltings.